Pneumatic shifting-force assistance devices of the type mentioned in the foregoing are used in particular in heavy trucks. They unburden the driver of the vehicle in question by greatly reducing the force that has to be applied by him on the gearstick in order to engage a gear or to change gears. Various such shifting-force assistance devices exist in practice. Pneumatic shifting-force assistance devices of the type mentioned in the introduction are known, for example, from DE 19539471 A1 and a series of protective rights based thereon, such as DE 19839850 A1, EP 1108166 B1, EP 2068044 A2 and EP 2076695 B1, to which reference is made with regard to the constructive details as well as the function.
Specific aspects and in particular a specific problem such as exists for pneumatic shifting-force assistance devices of the type under consideration here are set forth and discussed in DE 102011015713 A1, to which reference is again made and from which contents are adopted. To improve the functionality of the shifting-force assistance devices known up to that time, it is proposed therein to provide flow-through throttle passages on the piston structures (which are guided sealingly and displaceably on the output unit) as well as—associated functionally and spatially with the piston structure in question—respectively one throttle slide, wherein the throttle slide is respectively displaceable relative to the piston structure in question and is biased by means of a spring into a position closing the throttle passages. Depending on the position of the throttle slide relative to the associated piston structure, a defined cross-sectional area of the throttle passage is adjusted. The position of this throttle valve relative to the piston structure depends on the position of the piston structure (which is coupled with the control rod) relative to the output unit. This is achieved by the fact that the throttle slide is stopped against the associated valve seat disposed on the output unit.
In view of the prior art explained in the foregoing, the object of the present invention is to provide a shifting-force assistance device of the type indicated in the introduction that exhibits the advantages associated with the shifting-force assistance device according to DE 102011015713 A1 but is also characterized by a simpler construction.